For some reason my computer's monitor will randomly decide not to go to sleep, and instead it will stay on until I turn the computer off. I've checked all my power/sleep settings, and they're configured as I'd like (and, like I said, this is just random -- sometimes it works). Has anyone else run into this issue and found a way to fix it? Just a minor problem, but I can't seem to figure it out.

For some reason my computer's monitor will randomly decide not to go to sleep, and instead it will stay on until I turn the computer off. I've checked all my power/sleep settings, and they're configured as I'd like (and, like I said, this is just random -- sometimes it works). Has anyone else run into this issue and found a way to fix it? Just a minor problem, but I can't seem to figure it out.

Motherboard and motherboard chipset would be a good place to start the investigation.

Here's a rather surprising quirk - sleep has not worked right with my own motherboard chipset - Intel G41 - UNTIL Windows 8/8.1; that is despite the chipset itself being designed with Windows 7 in mind.

Backstory - Intel G41 was code-named Eagle Lake and was the designed successor to G31 - Bear Lake. Like G3x, G4x is a CSM (corporate-stable/consumer-stable) chipset - therefore no support for overclocking. Also, G4x did not necessarily prevent the use of discrete GPUs - it was left up to the motherboard OEM. (The same is true of G3x.)

However, G4x has had issues with hibernation AND sleep in Vista and 7. (That's one big reason I refuse to go back to 7.)